Seven ferrocenyl complexes, in which one or more of the Cp ring protons have been substituted by strongly electron-withdrawing pentafluorophenyl groups, have been examined by temperature-dependent ⁵⁷Fe Mössbauer spectroscopy (MES) to determine both the electronic and dynamic effects of such substitution. The mean-square-vibrational-amplitudes of the metal atom have been expressed in terms of the dimensionless parameter ₣_z,T=k²<x_ave²>, where z=M for the Mössbauer data, z=X for the X-ray data, k is the wave vector of the gamma radiation, and <x_ave²> is the mean square amplitude of the metal atom vibration. The differences between the M and X values can be related to the effects of local (atomic) and non-local (molecular) contributions to the metal atom dynamics. The MES data also elucidate the vibrational anisotropy of the metal atom motion, which in all of the complexes examined is isotropic within the experimental error.

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Addition of boric acid to dissolver solution has been proposed for minimizing the criticality concern associated with reprocessing of fast reactor fuel. Extraction of uranium (VI) and plutonium (IV) from the resultant nitric acid – boric acid medium by a solution of tri-n-butyl phosphate (TBP) in n-dodecane (n-DD) has been studied at 298 K. The distribution ratios of uranium (VI) and plutonium (IV) were found to be comparable with those obtained in the absence of boric acid. Extraction of europium (III) from nitric acid – boric acid by a solution of 1.2 M TBP–0.2 M n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) in n-DD was also studied. The solubility limit of boric acid as a function of nitric acid concentration was determined and it was found to decrease from 61.5 g/L in 0.1 M HNO₃ to 32.4 g/L in 4 M HNO₃ at 303 K. Extraction of boric acid in 1.1 M TBP/n-DD and in a solution of 1.2 M TBP–0.2 M CMPO in n-DD was studied and it was found to increase with increase in the concentration of boric acid above ∼0.2 M. The study indicated that the interference of boric acid during the extraction of uranium (VI) plutonium (IV) by PUREX solvent and Eu(III) by TRUEX solvent was negligible and the added boric acid could be quantitatively retained in aqueous phase provided the boric acid concentration was fixed below 6 g/L (∼0.1 M) in the feed solution.

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Concentrations of organically-bound ¹⁴C in the tree-ring cellulose of a Japanese Cedar (Cryptomeria japonica) grown in a rural region of Kanazawa, Ishikawa prefecture, Japan (36.5°N, 136.7°E), were measured for the ring-years from 1989 to 1998 to study relationship between ¹⁴C concentrations in tree-ring cellulose and atmospheric CO₂ in a narrow region. An interesting result in comparing our data of tree-ring cellulose with those of atmospheric CO₂ is that the ¹⁴C concentration in tree-ring cellulose was close to the corresponding average from mid-June to early September of ¹⁴C concentrations in atmospheric CO₂. Furthermore, the ¹⁴C concentrations in tree-ring cellulose were found to be merely influenced by the drastic decrease of ¹⁴C concentrations in atmospheric CO₂ in winter, which might be caused by air pollution from the Asian continent and additional local fossil fuel contribution. These results suggest that the ¹⁴C concentration in tree-ring cellulose for a given growing year reflects the ¹⁴C concentrations of atmospheric CO₂ during the warm summer months.

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As a part of interest in the study of the neutron flux in biological environments, variations of slow neutrons with depth of water and soil were measured through the radioactivity induced in gold by ¹⁹⁷Au(n,γ)¹⁹⁸Au reaction. The measurements made for 0–100 cm in fresh water and 20–400 cm in sea water showed that the thermal neutron flux had a peak at around 10 cm depth and then gradually decreased with depth in water. The depth profile in seawater was almost the same as freshwater. In the case of soil made for 0–60 cm, thermal neutron flux showed a peak at 5 cm and decreased rapidly to 60 cm accompanying a shoulder-like shape during 10–30 cm range.

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The activation of gold by environmental neutrons was used to study the effect of concrete buildings on the neutron flux and to estimate the thermal neutron flux in and around the building of Kinki University Training Reactor. The results showed that three ceilings of 34 g cm^-2 thickness decrease the fast neutrons to 26% from its original value. However, the same reinforced concrete decreases the slow flux to only 62% from its original value. On the other hand, the thermal neutron flux at 283 m from the reactor center was two times higher than the environmental background. These results can give attention to the effect of concrete walls as a shielding around the reactors, especially those that have been hold near to the living environments.

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In the present review we show a series of recent studies with the aim of exploring the electronic and magnetic structure of materials with perovskite structure and strong magnetoresistance effect. The examined samples include Sr_2-xA_xFeMO₆ (A = Ca, Ba and M = Mo, Re, Ru) double perovskites with x = 0 and 0.1 and iron doped La_0.8Sr_0.2Fe_yCo_1-yO_3-δ cobaltate perovskites with 0 ≤ y ≤ 0.3. Besides understanding the basic electronic and magnetic interactions presented by these compounds, we have tried to trace nanoscale phase separation, which has been introduced as a key feature for both colossal and intrinsic tunneling magnetoresistance recently.

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